The Thomas test and other physical therapy hip flexor tests

The physical therapy Thomas test is one of the hip flexor tests, or hip mobility tests, physical therapists (PTs) use.

Hip flexor tests, including the Thomas test, are tools for PTs to look at strength, range of motion, functional movement, and mobility of the hip complex.

The Thomas test is a physical therapy evaluation, or more specifically a hip flexor evaluation, that is used to assesship function and range of motion (ROM), and then determine if the symptoms observed meet the criteria for any physical therapy diagnoses.

These tests have been used for years to help therapists gather as much data as possible to understand the full picture of their patients’ mobility and physical capabilities, diagnose the patient, and prescribe a course of treatment.

In this article, we will cover the Thomas test’s description, how it’s performed, its purpose, and, finally, provide guidance on how to interpret test results (i.e., what constitutes a Thomas test POAS diagnosis, or what a positive Thomas test result indicates). We will also provide excellent resources that PTs can consult to gather more information.

Common hip flexor tests

There are multiple uses for the Thomas test. Additionally, there are other ways to test hip mobility and function. Each test assesses different symptoms crucial for diagnosis.

Here are some of the common ways PTs use, conduct, and interpret hip flexor tests:

Thomas test

The Thomas test looks at the length and tension of the hip flexor group, namely the iliopsoas, rectus femoris, tensor fascia lata, and the sartorius musculature.

It is used to rule out hip flexion contracture. The Thomas test is a simple pass/fail test, used to determine a deficit or imbalance of the hip flexor musculature, by assessing the tension between one joint and two joint musculature around the hip.

How to conduct the Thomas test 

During the Thomas test, the patient lies supine on a table (with help from the clinician) and pulls one knee toward the chest in a 90-degree angle.

The patient will then slowly lower the affected leg, allowing it to extend at the hip and knee as far as possible, doing a Thomas test stretch.

The patient should maintain a neutral lumbar spine position to ensure the test is performed correctly.

Interpret test results

If the extended leg rises, rises and abducts, or the knee doesn’t straighten (or a combination of these findings), it indicates a positive test (or pass) for hip flexor tension/shortened length.

Modified Thomas test 

The modified version of the Thomas test goes a step further, and measures “a peak hip extension angle in all individuals and not just those with a hip extension deficit.”

This hip flexor test looks at the length and tension of the hip flexor group, namely the iliopsoas, rectus femoris, tensor fascia lata, and the sartorius musculature.

It is important to note, however, that the reliability of this test depends on the therapist stabilizing the patient’s pelvis while conducting the test.

How to conduct the modified Thomas test

The patient is positioned sitting at the end of an examination table.

The patient is then asked to lie down while bringing both knees to their chest.

They should then perform a posterior pelvic tilt-flat back. Differently from the original Thomas test, one limb should then be lowered towards the table while keeping the opposite tucked towards their chest.

Interpret test results

If the extended leg rises, knee doesn’t straighten, the leg rises and abducts (or a combination of these findings), it indicates a positive test for hip flexor tension/shortened length.

FABER test

FABER is an acronym—F stands for Flexion, A for Abduction, and E and R for External Rotation.

The FABER test, aka the Patrick test, is used to identify the presence of hip pathology to attempt to reproduce hip pain in the flexed, abducted, and externally rotated positions.

These pathologies can include sacroiliac (SI) joint dysfunction, posterior or anterior hip impingement, labral tear, or other specific hip pathology.

How to conduct the FABER Test 

The patient is in supine position and the involved leg is put into a figure 4 position.

The therapist stabilizes the pelvis on the opposite side and then provides sustained (and oscillatory) overpressure into further external rotation and posterior glide of the tested hip at the end of the range of motion.

Interpret test results

If the test reproduces the patient’s pain, it is a positive test, and can be interpreted based on the location and description of the patient’s pain.

Ober test

A hip flexor tightness test that is used to evaluate a tight tensor fascia lata (TFL) and iliotibial band (ITB) of a hip complex.

How to conduct the Ober test 

The patient lies on their side with the affected side on top with the bottom hip and knee flexed to maintain neutral lumbar position.

The physical therapist will start with the involved hip extended and abducted, and then slowly lower the leg toward the table (not allowing the hip to flex or internally rotate as the leg is lowered).

Like the Thomas test, both the original and modified versions, conducting this hip flexor test involves extending and stretching the leg.

Interpret test results

If the leg remains abducted, it is a positive test for a tight ITB and TFL.

Craig test 

This test is used to measure femoral anteversion (rotation of the femoral neck).

How to conduct the Craig test

The patient lies prone with the knee bent to 90 degrees.

The therapist rotates the hip internally and externally, palpating the greater trochanter to determine the point where it is most prominent.

Interpret test results

The test is interpreted by looking at the greater trochanter.

The angle of the hip where the greater trochanter is most prominent indicates either femoral anteversion or retroversion, which can affect hip alignment and movement patterns, and potentiate hip dysfunction.

Excessive femoral anteversion can lead to hip impingement and knee dysfunction.

Scour test 

This test is used to evaluate the hip for possible impingement or labral tears.

How to conduct the Scour test

The patient lies supine, and the therapist moves the hip through a range of motion while applying a compressive force, rotating the hip internally and externally.

Interpret test results

The test is positive if pain or clicking is present and may indicate labral pathology or hip impingement.

These physical therapy hip mobility and hip flexor tests help provide PTs insight into a patient’s pathology and functional limitations within the lumbopelvic and hip girdle complex.

The tests provide a platform unto which a therapist can perform their clinical decision making to decide best steps for treatment, determine any need for referral to a physician or other provider for further diagnostics, and to determine if any other external care is required.

This list of commonly used hip flexor tests, including the Thomas test,  may be a helpful reference guide when assessing hip mobility and dysfunction.

Sources 

1. Vigotsky, AD., Lehman, G., Beardsley, C., Contreras, B., Chung, B., Feser, EH. (2016). The modified Thomas test is not a valid measure of hip extension unless pelvic tilt is controlled. PeerJ 4:e2325 https://doi.org/10.7717/peerj.2325
2. Sahrmann, S., Azevedo, DC., & Dillen, LV. (2017). Diagnosis and treatment of movement system impairment syndromes. Brazilian journal of physical therapy, 21(6), 391–399. https://doi.org/10.1016/j.bjpt.2017.08.001

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